Where "COND" is any logical condition and "BLOCK" is a block of code that is executed as long as COND is true. Note that in Perl a block of code is always delimited with { and } so an example while loop might look like this

Please include the edition number when referencing pages in books as they can change between editions. Page 94 of the most recent (3rd) edition has nothing to say about if, elsif or else. But on page 113 it has the following examples of compound logical statements: